Washington Attic Insulation Guide
Everything homeowners in Seattle need to know about attic insulation — R-value requirements, costs, and rebates.
Climate Zone & R-Value Requirements
Washington falls in Climate Zone 4-marine, covering cities like Seattle, Spokane, Tacoma. The International Energy Conservation Code (IECC) requires a minimum of R-60 for attic insulation. ENERGY STAR recommends R-60 for maximum comfort and energy savings.
Energy Rates in Washington
Washington electricity averages 10.5 cents per kWh. This is below the national average, but insulation still pays back in 5–10 years for most homes.
Typical Insulation Costs in Washington
| Material | DIY (material only) | Professionally Installed |
|---|---|---|
| Blown-in Fiberglass | $480–$780 | $1,200–$1,800 |
| Blown-in Cellulose | $600–$960 | $1,200–$1,800 |
| Fiberglass Batts | $360–$600 | $960–$1,440 |
| Open-Cell Spray Foam | Professional only | $1,800–$3,000 |
| Closed-Cell Spray Foam | Professional only | $3,000–$5,400 |
*Estimates based on a 1,200 sq ft attic. Use our calculator for a personalized estimate.
Rebates & Incentives in Washington
Frequently Asked Questions
What R-value do I need in Washington?
Washington requires a minimum of R-60 per current building codes (IECC). ENERGY STAR recommends R-60 for best energy efficiency.
How much does attic insulation cost in Washington?
For a typical 1,200 sq ft attic, professionally installed blown-in insulation costs $1,200–$1,800. Use our calculator for a precise estimate based on your specific attic.
What is the best insulation type for Washington?
In Climate Zone 4-marine, blown-in cellulose or blown-in fiberglass are the most popular choices. They offer excellent coverage, good R-value per inch, and competitive pricing.
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